Device for treating filamentary material



June 25, 1946. c. DE BRABANDER 2,402,609

DEVICE FOR TREATING FILAMENTARY MATERIAL Filed April 10, 1942 INVENTOR,

ATTORNEY.

Patented June 25, 1946 DEVICE FOR TREATING FILAMENTARY MATERIAL Camiel de Brabander, Newport, Dcl., assignor to American Viscose Corporation, Wilmington, Del., a corporation of Delaware Application April 10, 1942, Serial No. 438,421

5 Claims. 1

This invention relates to improvements in the treatment of filamentary material, particularly running lengths thereof, and comprises improvements in means for heating such material. This invention is particularly concerned with the application of the improved heating means to filamentary material which is undergoing stretching, such as in the stretch-spinning processes of making artificial filaments.

In the manufacture of artificial filaments, particularly those made from viscose, cuprammonium cellulose, and vinyl resins, such as the vinyl acetate-chloride copolymer varieties, it has heretofore been the practice to subject the filament or filamentary bundle to stretching shortly after its extrusion from the spinneret orifices in order to impart improved characteristics, particularly higher strength and greater extensibility, to the artificial filament products. In some cases, particularly in those involving treatment of vinyl resin filaments, this stretching is performed upon the filaments either shortly after extrusion or at any subsequent stage, such as after storing, or even after shipping to a separate plant, the treatment in the latter event being effected upon a machine entirely distinct from the spinning machine. which the stretching is performed upon the filamentary material, it has heretofore been common to plasticize the filamentary material by subjecting it to a certain amount of heat. This heat is applied to the filamentary material while it is undergoing the stretching, such as by the application of a heated liquid stream, a surrounding envelope of heated air, or the like. Since the heat is applied to a course or length of the filamentary material undergoing stretching, the bundle of filaments is relatively compact and the transfer of heat into the central filaments in the bundle depends substantially entirely upon the conduction of the heat through the outer filaments to the center. As a consequence, the outer filaments have a higher temperature than those within the bundle with the result that the stretching affects the outer filaments differently than it does those at the interior of the bundle. The ultimate result is the production of a bundle of individual filaments having various strengths, extensibilities and other characteristics. In addition, the employment of heating liquids makes the machine sloppy and tends to strip back any broken filaments in the bundle. Both liquid and gas heaters have the disadvantage of requiring a rather bulky and clumsy arrangement of equipment.

It is an object of this invention to overcome Regardless of the locality or stage at these disadvantages by the application of an improved heating arrangement, thereby making it possible to obtain artificial filamentary material constituted of individual filaments having substantially the same characteristics, particularly the same strength and extensibility. It is also an object of the invention to impart the maximum improvement in such qualities as strength and extensibility and the like that are obtainable by stretching of artificial filamentary materials. Further objects of the invention will be a parent from the drawing and theldescription thereof hereinafter.

In the drawing, illustrative of the invention,

Figure 1 shows a preferred embodiment of the invention,

Figures 2, 3, and 4 show modifications of the invention,

Figure 5 shows an equivalent electrical circuit for the preferred embodiment of Figure 1,

Figures 6,7 and 8 show end views of various forms of electrodes.

In accordance with this invention, it has been found possible to obtain substantially uniform heating throughout the bundle of filaments by subjecting the filamentary material to a high frequency electric current. By inducing such a current within the bundle of filaments which are still wet with residual amounts of the spinning bath which generally contain such electrolytic substances, as acids and salts, substantially uniform heating occurs throughout the filamentary bundle since electrolyte is present fairly uniformly distributed throughout the bundle.

A high frequency electric current may be induced within a filamentary bundle in any suitable fashion, but it is preferred to induce it longitudinally of the bundle since it has been found that the most satisfactory results are thereby obtained.

As shown in Figure 1, the filamentary bundle 2,

as it comes from the spinneret i of an artificial filament spinning machine, such as that for making filaments from viscose, proceeds in succession about two godets 3 and l the second of which rotates at a higher speed than the former, thereby effecting stretching of the course of filamentary material extending therebetween. As the filamentary bundle passes from the first godet 3 to the second 4, it passes generally concentrically through a set of three electrodes 5, 6 and l, preferably equidistantly spaced from one another. These electrodes may have any suitable shape, those represented by the end views of Figures 6 to 8 being highly satisfactory, and those of Figures 6 and 8 having the advantage of being readily threaded.

Thetwo outer electrodes 5 and I may be grounded directly to serve as a guard to prevent current from flowing in the filament beyond the electrodes or, as shown in Figure 1, the frame of the machine may be grounded, as at 8 or 9 and the outer electrodes 5 and I may be connected by suitable conductors I and II to the frame. The middle electrode 6 is attached by a suitable electrical conductor l2 to one pole l3 of any suitable source I4 of high frequency electric current 3 such as a radio frequency oscillator. The other pole ii of the high frequency oscillator I4 is grounded at IS. The oscillator l4 may be connected to a suitable source of power by the conductors l1 and la.

The arrangement of Figure 1 constitutes essentially a capacitive coupling of the high frequency oscillator M to the traveling filamentary bundle 2. Essentially, the two lengths a and b of filamentary material extending between the central electrode 6 and the outer two and I act as resistances l9 and 20 between pairs of condensers 2 I, 22 and 22, 23 respectively as shown in Figure 5. By suitably spacing the electrodes, the amount of current flowing longitudinally between the adjacent electrodes may be varied to obtain the desired heating effect. Since a certain amount of drying may be effected by passage between the first and second electrodes, the conductivity of the filamentary bundle as it proceeds from the second to the third electrodes may in some cases be considerably different from that of the same length of filamentary bundle as it passes between the first two electrodes. For this reason, it may be desirable to have the first and second electrode at a different distance from each other than the distance between the second and third electrodes. However, this depends upon the particular nature of the residual solution carried by the filamentary bundle, and ordinarily the conductivity is not so greatly changed between the successive pairs of electrodes that the equidistant spacing is unsatisfactory.

Figure 2 shows a modification in which only two electrodes 25 and 26 are employed, each of which i connected to a distinct pole of the oscillator l4. A thread guide may be employed at any point along the course of travel of the filamentary material between the two godets 3 and 4 to assist in maintaining the bundle of filaments generally concentrically within the electrodes. A plurality of such guides, one on either side of each electrode, may be employed since such guides are ordinarily made of an insulating material, such as porcelain, glass, and the like, Figure 2 shows an arrangement in which one such guide 21 is placed between the second electrode 26 and the upper godet 4 and, in place of using another guide between the godet 3 and electrode 25, a wiping guide 28, which may comprise a U-shaped support holding a pair of belt or fur pads sandwiched therein may be suited for, wiping the filamentary material as it passes therebetween. This wiping arrangement removes any excess liquid, especially any drops or globules thereof clinging to the filamentary bundle and thereby prevents any flashover from either of the electrodes to the filamentary bundle by way of the path formed by the globule upon the filamentary material.

Figure 3 shows a modification corresponding to that of Figure 1, but in which the two outer electrodes 5 and 1 are not grounded but are directly connected to the pole l5 of the oscillator 14 while the central electrode 6 is connected to the other pole l3 thereof.

Figure 4 shows a modification employing a greater number of electrodes, those (29 and 30) connected to one pole l3 of the oscillator l4 alternating with those (3|, 32 and 33) connected to the ground, the other pole l5 of the oscillator being connected to the ground. The invention is amenable to the employment of any number of electrodes connected in the fashion shown.

The electrodes, as shown in Figures 6 to 8 inclusive, comprise a conductor 34 in the form of a suitably shaped plate, such as of metal, which is covered with suitable insulation 35, such as glass, which not only protects the metallic plate from corrosion by the gases, vapors and liquids present around an artificial filament spinning machine, but also serves the purpose of preventing corona discharge.

Any high frequency oscillator may be employed, an oscillator producing currents in the range of radio frequencies being preferred. For example. an oscillator producing a current having a frequency of the order of five to six megacycles up to 25 to 60 megacycles or so and operating at a voltage from 1000 to 50,000 volts, a voltage of the order of 2000 to 3000 being preferred, has been found to render highly satisfactory service in this application.

The filamentary products obtained by the treatment in accordance with this invention exhibit a high degree of uniformity with respect to the individual filaments in the bundles, such as those obtained by extrusion through spinnerets having a plurality of orifices. This invention also makes it possible to obtain the maximum degree of the desired quality, such as strength or extensibility, obtainable in the filamentary bundle by such stretch treatments. This results from the fact that the high quality imparted to any concentric stratum of filaments within the bundle is not averaged down by a lesser degree of the properties obtained in the filaments at other strata (outer or inner) within the bundle by virtue of non-uniform heating at the time of stretching. Instead, the maximum degree of the characteristics intended to be imparted to the filaments are obtained in not only individual filaments in the filamentary bundle but uniformly in all'with the result that the product as a whole has the optimum qualities obtainable by the stretching process.

While the invention has particular advantages in relation to the stretch-spinning processes, whether it is applied substantially immediately after extrusion from the spinnerets or at a much later stage of manufacture in the production of artificial filaments, nevertheless, the improved heating arrangement shown and described hereinabove may be applied for other purposes, particularly for drying running courses of filamentary material. Although the disclosure has specifically referred to the production of such artificial filamentary material as that obtainable from viscose, cuprammonium cellulose, and vinyl resins, particularly vinyl acetate-chloride copolymers, it is applicable also to filamentary material made up of cellulose derivatives, such as cellulose acetate, ethyl cellulose, of nylon, and of proteinous materials, particularly casein. The heating arrangement may also be applied to natural filamentary material, such as tows or yarns made of or comprising cotton, wool, and silk for drying or stretching thereof. It may also be applied in treating yarns or other filamentary material constituted of mixtures of artificial and natural fibers, particularly those of mixtures spun or otherwise produced with a minor proportion of more or less thermoplastic fibers or filaments which are adapted to be converted by the heating to a somewhat softened state in which they effect a binding together of the other non-thermoplastic filaments or fibers within the filamentary structures. It may also be applied in the crimping and creping of filamentary structures where crimping or creping agents, particularly differential creping agents, are first applied to the filamentary material and are then adapted to be crimped or creped solely by the application of heat. In any of such applications, where the filamentary structure does not contain suflicient conductive liquids to make them amenable to treatment in accordance with the invention, they may first be wetted with water or an aqueous solution of a salt or acid to increase their conductivity and to thereby enhance the conductivity of the filamentary structure.

While preferred embodiments of the invention have been shown, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. The method of producing artificial filaments comprising extruding the filament-forming material through a spinneret into a liquid coagulating bath, passing the formed filamentary material through a predetermined path, removing coagulating liquid therefrom along a portion of the path, and applying to the bundle capacitatively a high frequency alternating current as it passes along a subsequent portion of the path, and stretching the material in the vicinity of the latter portion of the path.

2. The method of producing artificial filaments comprising extruding the filament-forming material through a spinneret into a liquid coagulating bath, passing the formed filamentary material through a predetermined path, removing coagulating liquid therefrom along a portion of the path, and applying to the bundle capacitatively a high frequency alternating current as it passes along a subsequent portion of the path, the time of passage through the latter portion of the path being adjusted to eflect drying of the material.

3. The method of producing artificial filaments comprising extruding the filament-forming material through a spinneret into a liquid coagulating bath, passing the formed filamentary material through a predetermined path, removing coagulating liquid therefrom along a portion of the path, and applying to the bundle capacitatively a high frequency alternating current as it passes along a subsequent portion of the path, the time of P sage through the latter portion of the path being adjusted to eflect drying of the material,

and stretching the material in the vicinity of the latter portion of the path.

4. An apparatus for treating filamentary material comprising mean for stretching a running course of the material, means for inducing a high frequency electric current in the running course of the filamentary material, and means in ad- Vance of the induction means for removing liquid from the material.

5. An apparatus for treating filamentary material comprising means for stretching a running course of the material, means for producing a high frequency electric current, means for capacitatively coupling said current with said filamentary material, said coupling means comprising at least two insulation-covered metallic electrodes spaced longitudinally of the course of said filamentary material, and means in advance of the induction means for removing liquid from the material.

CAMIEL or: BRABANDER. 

